Shrink and Cling Packaging

1. Dr. R. T. Patil
Central Institute of Agricultural
Engineering, Bhopal
Shrink and Cling Packaging of
Fresh and Perishable Foods

2. Production and Post Harvest
Scenario
•Agriculture contributes about 17% of GDP and
sustains approx over 60% of population
•India produces about 240 million tons of food
grains (Approx 10% loss) and 53.1 and 91.6
million tons of fruits and vegetables and ranks
second in world (Approx 25-40% loss)
•Low level of processing of fruits and vegetables
at only 2.2% and packaging is also neglected
area.
•Food processing is employment intensive,
creates 1.8 jobs directly and 6.4 indirectly for
every US$ 25000 invested.

3. Estimated Post-harvest Losses
Type of food
commodity
Present level of production Post-harvest
losses
Quantity
Mt
Ave.
price
Rs/t
Value
million
Rs.
crores
% Quantity
Mt
Monetary
value Rs.
Crores
Durable (cereals,
pulses and
oilseeds)
230 10000 230000 10 23 23000
Semi-perishables
(potatoes, onion,
sweet potato,
tapioca)
40 3000 12000 15 6 1800
Perishables (Fruits,
vegetables, milk,
meat, fish and
eggs)
210 15000 315000 20 42 63000
Total/Average 480 11604 557000 14.8 71 87800
Source: Kachru, 2005

4. Polymers in Food Packaging
• Individual wrapping of produce in plastic film is used for
extending post harvest life of fruits and vegetables. Such
packaging increases the resistance to water vapour and
transpiration loss from the fruit surface.
• It enhances the effectiveness of fungicide by slowing down its
dissipation rate when fungicide treated fruits
• Produces a micro atmosphere and acts as modified
atmosphere chamber under ambient condition for each fruit to
control decay over a prolonged period.
• Polyvinyl chloride (PVC) film has long been the film of choice
in the food wrap industry.
• The films made of low density polyethylene are being used in
stretch packaging.
• Laminated films comprising two or more layers of different
materials having differing characteristics are used.

6. Shrink Packaging
• Shrink wrap packaging is practiced either individually or as
tray over wrap packaging.
• Individual shrink-wrapping produces a micro atmosphere that
can control decay over a prolonged period.
• In case of tray wrap packaging, retardation of senescence
through modification of in-package atmosphere is one of the
potential benefits.
• Film is shrink wrapped tightly around each piece to form a tight
and smooth package of each fruit making it as another layer of
protective cuticle.
• Packaging increases the resistance to water vapour and
transpiration loss from the fruit surface. It enhances the
effectiveness of fungicide by slowing down its dissipation rate
• It not only extends the shelf life but also reduces the
refrigeration cost and can be alternative to refrigerated
storage.

7. Advantages of Shrink Packaging
• Reduces water loss and maintain freshness of fruits.
• The whole fruit surface can be examined prior to
purchase
• Prevents secondary infection, important for long term
storage
• Reduces chilling injury during cold storage.
• Saves storage energy by storing at higher temperature
• Produce remains free of contamination until consumption
• Avoids condensation of droplets inside the package
• Spoiled fruit can be discarded easily.
• Delays ripening and undesirable colour development
• Avoids physical damage during rough handling
• Minimizes the use of chemicals.
• Better consumer appeal and thus fetch higher price

8. Process of Shrink Packaging
• Initially the fruits are sealed in a suitable film with the
help of impulse sealer.
• They are then passed through the tunnel of shrink
packaging machine to form a tight wrap.
• Temperature of tunnel is maintained between 180-
210oC for individual wrap and 140-145oC for tray wrap.
• In both the cases, the duration of heat exposure varies
between 15-30 sec depending upon the thickness of
the film used for shrink wrapping and its sensitivity to
heat shrinkage
• Subjecting the produce beyond this temperature will
result in tissue injury.
• Shrink-wrapped fruits are immediately cooled to
remove the excess heat for 2-3 hours at 5-10oC.

9. Properties of Shrink Wrapping Film
• Low permeability to
water.
• Low thickness with
high tensile
strength.
• Low permeability to
O2 and high
permeability to
CO2.
• Glossy and
transparent.
• Shrinks at low
temperature.
Permeability to Oxygen and
Carbon-dioxide
Polyfilm type Permeability
Oxygen Carbon
dioxide
Polyester 50-130 180-390
Pliofilm 130-
1300
520-5200
Polypropylene 1300-
6400
7700-
21000
Polystyrene 2000-
7700
10000-
26000
Polyethylene 3900-
13000
7700-
77000

10. Shelf Life of Shrink Wrapped
Fruits and Vegetables
Commodity Film
thick
ness
Shelf life
Cold storage
(weeks)
Ambient storage
(days)
Un-
wrapped
Wrapped Un-
wrapped
Wrapped
Kinnow 25 m 15 30 6 10-12
Capsicum 20 m 5 17 3 6-7
Tomato 15 m 9 19 3 5-6
Guava 25 m 5-7 12 2 3-4
Peach 20 m 6-7 15 2 4-5
Apple 25 m 12 30 14 18-20
Pomegranate 20 m 10 25 6 12
Ramesh Kumar, CIPHET,2009-11

11. Cling Packaging
• In cling packaging food products, particularly fresh
meat and produce, are wrapped in transparent,
thin film.
• The film must be both transparent to provide an
aesthetically pleasing look and sufficiently strong to
provide the protection.
• A crystal clear, transparent film is desired to
provide a visually attractive wrapping for the
produce.
• The elasticity of the film must maintain the
stretched film in a tight fit about the product and
exhibiting good recovery from deformation.

12. Process of Cling Packaging
•Intermittent, high speed removal of film from a
supply roll,
•the pushing of a tray filled with food upward
until it impacts against the film,
•the stretching of the film around the tray to the
lower side thereof and sealing of the film.
•The film may be sealed by clinging to itself or
by heat sealing the edges of the film.

13. Films for Cling Packaging
Polyvinyl chloride (PVC) film has long been the film of choice in
the food wrapping. They are difficult to dispose of as they are
made with heavy metals like lead and cadmium; less than 1
percent of it is recycled.
• Films made of low density polyethylene have also been used but
they are often rigid, have low elongation and low tear strength.
• Ethylene vinyl acetate films are also used but they suffer from poor
tear resistance.
• High density polyethylene (HDPE) is much too inelastic to be
useful as a commercial wrap
• Linear low density polyethylene (LLDPE), ultra low density
polyethylene (ULDPE), etc., do not possess sufficient elastic
recovery, and the film retains impressions or dents caused by
handling
• The multiple layer laminated films comprising two or more layers of
different materials having differing characteristics are bring
developed for this use.

14. Shrink Wrapping Demonstration

15. 6
20
12
32
0
5
10
15
20
25
30
35
Shelflife(days)
Control Shrink wrap
Shelf life of shrink wrapped mango
RT
CS